His parents have been plunged into grief by the death, Hussein Buhidma confirmed.

"He was killed fighting, he was killed in Syria," he said. "His parents are friendly people but at the minute they are a bit upset and they want to be left to grieve for a couple of days."

Shamseddin moved to Ireland from Libya with his family in 2001. His father Ibrahim runs a Halal grocery shop in Navan, Co Meath.

Mr Gaidan told the Irish Times: "We don't know where or how he was killed and we don't know where his body might be. It is very difficult to get any information. This confusion makes our grief much worse."

The teenager spent his summer holidays in Libya last year and was supposed to fly back to Ireland via Istanbul in mid-August. His family raised the alarm when he did not arrive in Dublin. They later learned he had crossed the Turkish border into Syria.

Mr Gaidan said: "We heard nothing from him until one day someone called from Syria saying Shamseddin is here and he is helping the Syrian people."

The last Mr Gaidan heard from Shamseddin was a brief phone call some time later during which he entreated his son to return home. "He refused, saying how could he leave when the Syrian regime was killing its own people, including children," he added.

Mourners gathered at Tallaght mosque in Dublin this week to offer condolences to the Gaidan family. Prayers were also offered at St Patrick's Classical School in Navan, where Shamseddin had studied.